Telegraph: In the West Midlands dead fish were found floating in a park due to oxygen depletion from the algae and the fountains in Trafalgar Square had to be closed because of the green slime. It has also caused trouble for gardeners and fishermen. Vets have now raised concerns that dogs diving into lakes and ponds are at risk of being poisoned by ingesting a toxic blue green algae called Cyanobacteria. Mark Johnston, of the British Small Animals Veterinary Association, warned pet owners …